A storage control unit has a role of providing control and connection management of an aggregation of disks to client computing systems. The storage control unit is able to identify and parse out the required amount of storage capacity to a given client computer via some administrative interface.
Client computer systems handle write data at file level via a file system implemented by the client computer systems. Using the file system and structure client computers may employ a cache system for storing write data at file level prior to converting to block level addresses and writing the data to backing storage disks. Such cache systems secure data and are sometimes employed to provide for data comparison and integrity verification and are tightly integrated with client computing systems and file structures of those systems. Such cache systems do not address block level protocol data storage or potential failure and recovery of storage control units operating using address block level protocol.
The storage control unit provides the data transport medium (channels) to the disk drives. In this role, the storage control unit serves as the intermediary between the storage and the client computer systems that store and retrieve data to and from the storage subsystem. The storage control unit (channel) transport connection to the storage devices are commonly physical SCSI, Serial Addressed SCSI (SAS), or Fibre Channel connection, though other physical device connection types do exist.
The storage control unit, in turn, provides client computing systems a similar “channel” connection, such as ESCON, FICON, SCSI, SAS, or Fibre Channel. Again, these examples represent the more common connections of the larger set of channel transport available in computing at the time of the patent submission.
A single or multiple set of control units 1 to “n” provide benefit to host systems by presenting a centralized, robust, intelligent, and programmed interface representing a managed storage pool. This interface simplifies the management of storage for the client computers. The storage control unit(s) often provides a logical representation of storage independent of the topology and geometry of the disk drives. Additionally, it is frequently found that control units also provide data protection via RAID provisions and other storage management functions.